To Dose or Not to Dose?

Robert DavidsonEditor-in-Chief

US Pharm. 2019;44(2):5.

Heeding the advice of their physicians, many healthy older adults seeking protection from heart attack and other cardiovascular dangers take a daily low-dose aspirin. The well-intentioned routine, however, might actually put them in danger: A recent study in the Journal of the American Medical Association (JAMA) finds that taking aspirin on a regular basis to prevent heart attacks and strokes can lead to an increased risk of almost 50% in major bleeding episodes.

The systematic review from scientists at King’s College London and King’s College Hospital evaluated the overall impacts on patients without known cardiovascular disease. The researchers discovered that while daily low-dose aspirin was linked with a lower risk of heart attacks and other cardiovascular events, the protocol also perpetuated an increased major bleeding risk.

Despite findings that aspirin lowers risks for persons who previously suffered strokes and heart attacks, the evidence of the role of aspirin in initially preventing cardiovascular events is not on solid footing. The British study looked at the outcomes of trials enrolling more than 1,000 subjects with no known history of cardiovascular diseases and featured a 12-month follow-up. Some subjects took aspirin, while others took a placebo or had no treatment.

The study found that while aspirin use was tied to an 11% lower risk of cardiovascular events, it was also associated with a 43% risk of major bleeding events when compared with subjects who did not take aspirin. No effect was seen with aspirin, the study investigators reported, on new cancer diagnoses or deaths.

This month’s CE article (page 37), “Assessing Aspirin for Primary CVD Prevention,” by Jelena Lewis, PharmD, Laressa Bethishou, PharmD, BCPS, andLaura Tsu, PharmD, BCPS, BCGP, also comes down on the side of caution concerning aspirin’s utility as a preventive tool against primary cardiovascular disease. The role of aspirin is much better defined for secondary prevention, the authors point out, compared with the goal of forestalling a first heart attack or stroke.

According to Lewis and colleagues, this is because the benefits of aspirin for secondary events outweigh the risks for bleeding, while in primary prevention this risk-benefit assessment of aspirin remains inconclusive (or even perilous, as in the JAMA study). The three studies published in 2018 and discussed throughout the article attempt to better define aspirin’s role for primary prevention of cardiovascular events. Their findings, the authors add, were “in line with many of the previously published studies, which found that the benefits of aspirin do not outweigh the risks when it comes to primary prevention.”

The authors conclude that using aspirin for primary prevention should be based on a patient’s preference, risk factors, and financial barriers. Moreover, they emphasize that the decision to use daily low-dose aspirin for primary prevention, especially for patients at low risk for cardiovascular dis